Set Advanced Search Form static fields to default "contains"?

I’ve just started using the Advanced Search module on our site, and for the form fields (the static ones that appear like title/author/subject, not the fields with the drop-down options) I’d like these to default to a “contains” operator. They currently seem to default to “is exactly”.

In the search page config I see that the operator for “contains” is “in”, and I’ve tried adding that into the strings in the Advanced Form > Filters area (example strings I’ve tried below), but it’s not working so far and would appreciate any help!

dcterms:creator = Creator = in =
dcterms:creator = Creator = in