POST /enwiki/_search
{
   "fields": [
      "namespace",
      "title"
   ],
   "query": {
      "filtered": {
         "filter": {
            "bool": {
               "must": [
                  {
                     "term": {
                        "namespace": "8"
                     }
                  },
                  {
                     "regexp": {
                        "title.keyword": ".*\\.(js|css)"
                     }
                  },
                  {
                     "script": {
                        "script": "_source['text'].contains('mw.user')"
                     }
                  }
               ]
            }
         }
      }
   }
}