Query with must and should with ANd and OR Logic in Elasticsearch

[Rakhshunda_Noorein_J (Rakhshunda Noorein Jawaid)]

Hi,
I want my search work like all the search terms searched with AND results first and then with OR results.

example,
Search term - borosil infrastructure
the result should come like -

borosil infrastructure
borosil infrastructure ltd
private sector borosil infrastructure
borosil ltd
borosil carp
infrastructure ltd
infrastructure info

first i am giving preference to AND results then OR...

My query is

{
  "from": 0,
  "size": 100,
  "query": {
"function_score": {
  "query": {
    "bool": {
      "must": [
        {
          "multi_match": {
            "query": "example",
            "fields": [
            "field1^6","field1._2gram","field1._index_prefix^12",
            "field2^2","field2._2gram^4","field2._index_prefix"
            ],
            "type": "bool_prefix"
          }
        }
      ],
      "should": [
        {
          "multi_match": {
            "query": "example",
            "fields": [
            "field1^6","field1._2gram","field1._index_prefix^12",
            "field2^2","field2._2gram^4","field2._index_prefix"
            ],
            "type": "bool_prefix",
            "operator": "and",
            "boost": 1000
          }
        }
      ],
      "filter": {
          "bool":{
              "must":[
                {
                    "term": {
                        "Field3": 0
                    }
                },
                {
                    "term": {
                        "Field4": 1
                    }
                }

              ]
          }
      }
    }
  },
      "functions": [
        {
          "filter": {
            "match_all": {
              "boost": 1
            }
          },
          "script_score": {
            "script": {
              "source": "doc['P_score'].value != null && doc['P_score'].value !=0 ? (doc['P_score'].value * 100000) + (doc['W_score'].value * 100000) : (doc['W_score'].value * 100000)",
              "lang": "painless"
            }
          }
        }
      ],
      "boost": 1,
      "boost_mode": "avg",
      "score_mode": "avg"
    }
  },
  "sort": [
    {
      "_score": {
        "order": "desc"
      }
    }
  ]
}

the results are coming as per desired in some cases but in some cases its not behaving as needed.

then I changed the query with AND in must and Or in should

"query": {
"bool": {
"must": [
{
"multi_match": {
"query": "example",
"fields": [
"field1^6","field1._2gram","field1._index_prefix^12",
"field2^2","field2._2gram^4","field2._index_prefix"
],
"type": "bool_prefix",
"operator": "AND"
}
}
],
"should": [
{
"multi_match": {
"query": "example",
"fields": [
"field1^6","field1._2gram","field1._index_prefix^12",
"field2^2","field2._2gram^4","field2._index_prefix"
],
"type": "bool_prefix",
"operator": "OR"
}
}
]

but It end up in showing only AND results.. and no OR results are coming...