Ok, so I have a magic answer.
Make a formula rich field type and concatenate all the fields that you want to search into one field and make a fake hyperlink. The field will be searchable but invisible to the naked eye.
Add the field as the last column of the report and either override the column heading with a dot for a label or just call the field [.]
It will be a skinny field at the end of the report that no one will notice but magically all the extra fields you need searched will be searched using the filter box.
var text URL = List(" ", [sub 1], [sub 2], [sub 40]); // put the extra fields to be searched here
var text Words = "";
"<a href=" & $URL & ">" & $Words & "</a>