MC-21228: Support partial word search in Elasticsearch

- Added partial search for skus

Author: Prabhu Ram

app/code/Magento/CatalogSearch/etc/search_request.xml

@@ -23,7 +23,9 @@
                 <match field="*"/>
             </query>
             <query xsi:type="matchQuery" value="$search_term$" name="partial_search">
+                <match field="*"/>
                 <match field="name" matchCondition="match_phrase_prefix"/>
+                <match field="sku" matchCondition="match_phrase_prefix"/>
             </query>
             <query xsi:type="filteredQuery" name="category">
                 <filterReference clause="must" ref="category_filter"/>