How to search through ingest attachments

Hello, i'm installed elastic and ingest plagin but can't understand how to search through indexed attachments. Can you please explain how to build search query for attachments content?

PUT _ingest/pipeline/attachment?pretty
{
 "description" : "Extract attachment information from arrays",
 "processors" : [
   {
     "foreach": {
       "field": "attachments",
       "processor": {
         "attachment": {
           "target_field": "_ingest._value.attachment",
           "field": "_ingest._value.data"
         }
       }
     }
   }
 ]
}

PUT article/_doc/1?pipeline=attachment&pretty
{
 "attachments" : [
   {
      "filename" : "test_1.txt",
      "data" : "UEsDBBQACAgIACtHzU4AAAAAAAAAA*****"
    }
 ]
}

GET article/_doc/1?pretty
{
    "_index": "article",
    "_type": "_doc",
    "_id": "1",
    "_version": 2,
    "_seq_no": 39,
    "_primary_term": 3,
    "found": true,
    "_source": {
        "attachments": [
            {
                "filename": "test_1.txt",
                "data": "UEsDBBQACAgIACtHzU4AAAAAAAAAAAAAA*****",
                "attachment": {
                    "content_type": "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
                    "language": "hu",
                    "content": "Hello, find me!",
                    "content_length": 16
                }
            }
        ]
    }
}

Then trying

GET article/_search
{
  "query": {
    "match": {
      "attachments(or content or attachment etc)": {
        "query": "hello"
      }
    }
  }
}

But return 0 hits

You need to fully specify the path within the document to the field you want to search. Try adjusting your query to:

GET article/_search
{
  "query": {
    "match": {
      "attachments.attachment.content": {
        "query": "hello"
      }
    }
  }
}