Search in all paths in a nested query

[hanisaf]

I have a document that contains multiple nested fields. I want to write a generic query to match a keyword in all nested fields and return inner hits. Is there a way to use _all in path and/or fields. i.e to write something like:

GET mydocs/_search
{
  "query": {
    "nested": {
      "path": "_all",
      "query": {
        "bool": {
          "must": [
            { "match": { "_all": "keyword" }}
          ]
        }
      },
      "inner_hits": { 
        "highlight": {
          "fields": {
            "_all": {}
          }
        }
      }
    }
  }
}