diff --git a/packages/strapi-plugin-upload/services/Upload.js b/packages/strapi-plugin-upload/services/Upload.js
index 3e3f8dfd82..e1012b9519 100644
--- a/packages/strapi-plugin-upload/services/Upload.js
+++ b/packages/strapi-plugin-upload/services/Upload.js
@@ -233,6 +233,12 @@ module.exports = {
   },
 
   fetchAll(params) {
+    // FIXME: until we support boolean operators for querying we need to make mime_ncontains use AND instead of OR
+    if (_.has(params, 'mime_ncontains') && Array.isArray(params.mime_ncontains)) {
+      params._where = params.mime_ncontains.map(val => ({ mime_ncontains: val }));
+      delete params.mime_ncontains;
+    }
+
     return strapi.query('file', 'upload').find(params);
   },
 
diff --git a/packages/strapi-utils/lib/convertRestQueryParams.js b/packages/strapi-utils/lib/convertRestQueryParams.js
index 40a7c4d535..6b2faa5d26 100644
--- a/packages/strapi-utils/lib/convertRestQueryParams.js
+++ b/packages/strapi-utils/lib/convertRestQueryParams.js
@@ -12,9 +12,7 @@ const _ = require('lodash');
 const convertRestQueryParams = (params = {}, defaults = {}) => {
   if (typeof params !== 'object' || params === null) {
     throw new Error(
-      `convertRestQueryParams expected an object got ${
-        params === null ? 'null' : typeof params
-      }`
+      `convertRestQueryParams expected an object got ${params === null ? 'null' : typeof params}`
     );
   }
 
@@ -36,12 +34,18 @@ const convertRestQueryParams = (params = {}, defaults = {}) => {
     Object.assign(finalParams, convertLimitQueryParams(params._limit));
   }
 
-  const whereParams = _.omit(params, ['_sort', '_start', '_limit']);
+  const whereParams = _.omit(params, ['_sort', '_start', '_limit', '_where']);
+  const whereClauses = [];
 
-  if (_.keys(whereParams).length > 0)
-    Object.assign(finalParams, {
-      where: convertWhereParams(whereParams),
-    });
+  if (_.keys(whereParams).length > 0) {
+    whereClauses.push(...convertWhereParams(whereParams));
+  }
+
+  if (_.has(params, '_where')) {
+    whereClauses.push(...convertWhereParams(params._where));
+  }
+
+  Object.assign(finalParams, { where: whereClauses });
 
   return finalParams;
 };
@@ -52,9 +56,7 @@ const convertRestQueryParams = (params = {}, defaults = {}) => {
  */
 const convertSortQueryParams = sortQuery => {
   if (typeof sortQuery !== 'string') {
-    throw new Error(
-      `convertSortQueryParams expected a string, got ${typeof sortQuery}`
-    );
+    throw new Error(`convertSortQueryParams expected a string, got ${typeof sortQuery}`);
   }
 
   const sortKeys = [];
@@ -87,9 +89,7 @@ const convertStartQueryParams = startQuery => {
   const startAsANumber = _.toNumber(startQuery);
 
   if (!_.isInteger(startAsANumber) || startAsANumber < 0) {
-    throw new Error(
-      `convertStartQueryParams expected a positive integer got ${startAsANumber}`
-    );
+    throw new Error(`convertStartQueryParams expected a positive integer got ${startAsANumber}`);
   }
 
   return {
@@ -104,13 +104,8 @@ const convertStartQueryParams = startQuery => {
 const convertLimitQueryParams = limitQuery => {
   const limitAsANumber = _.toNumber(limitQuery);
 
-  if (
-    !_.isInteger(limitAsANumber) ||
-    (limitAsANumber !== -1 && limitAsANumber < 0)
-  ) {
-    throw new Error(
-      `convertLimitQueryParams expected a positive integer got ${limitAsANumber}`
-    );
+  if (!_.isInteger(limitAsANumber) || (limitAsANumber !== -1 && limitAsANumber < 0)) {
+    throw new Error(`convertLimitQueryParams expected a positive integer got ${limitAsANumber}`);
   }
 
   return {
@@ -141,6 +136,12 @@ const VALID_OPERATORS = [
 const convertWhereParams = whereParams => {
   let finalWhere = [];
 
+  if (Array.isArray(whereParams)) {
+    return whereParams.reduce((acc, whereParam) => {
+      return acc.concat(convertWhereParams(whereParam));
+    }, []);
+  }
+
   Object.keys(whereParams).forEach(whereClause => {
     const { field, operator = 'eq', value } = convertWhereClause(
       whereClause,