What is the alternative way of querying _all?

From elasticsearch 6.x _all has been deprecated. I have a matchQuery like below

                        .should(QueryBuilders.matchQuery("_all", typeAndName.name))
                                dataModel.getLowerFieldName(PropertyType.STRING, SearchFields.kObjectNameKey),

Can someone suggest someway what is the recommended way of doing the same now?

I am using dynamic mapping. So as mentioned in doc I don't know beforehand what all fields can be there in the index so I cannot use copy_to in index mapping to copy all fields data to some other field to simulate all.