Multi-Match Bool Prefix Query - search query for search-as-you-type and keyword fields

Hi,
I want to find out, how multi match works for search-as-you-type and keyword type fields in one query. If I make multi match query on only search-as-you-type fields, I get expected result.
If only, I make query which contains two words which match both types (search-as-you-type and keyword), I get unexpected results.

I can't change mapping in elasticsearch, so I have to find appropriate way to execute multi-match search query on both types.

I want to ask, If exists any rule for this query?
Is there any recommend way to execute multi-match search query for search-as-you-type and keyword fields?