Best way to contains search in elastic search

I am working on a use case which does contains search in logs data indexed in elastic server. the query is a case-insensitive one

I am aware of match, match_phrase and query string. But none of the seems to be working for my use case.

can any one suggest how to contains search in Elasticsearch.

Have you looked at using the wildcard field type which as far as I can tell could be a good fit?