without limiting to a specific field: like schmidt~
with limit to a specfic field: str_stringfieldname like schmidt~
The fieldname identifier is constructed as follows: datatype-abbreviation (e.g. str means string) + "_" + technical fieldname (if the field comes from an abstract type, if must be the technical name of the abstract type + "_" + technical fieldname)
If the field is a catalog entry, you also need to append "_" + language-abbreviation (e.g. en for english or de for german)
It is easiest to just look up the fieldsnames in the elasticsearch index. For that navigate to http://<elasticsearch-ip>:9200/enaiored/_doc/<object-itemID> and see which fields are available.