Searching problem: User-Defined Keywords

[quant]

Motivation:
How should I create the following search:

"whatever attribute"(except (Item) attribute) contains keywords ...
AND/OR "user-defined Keywords" contains ... ?

The second part of the search can be created by using (Item) contains keywords ... + ticking option "Search only user-defined keywords".

But once you tick "Search only user-defined keywords" the first part of the search doesn't work as I wanted it to work (because no attribute has "user-defined" keywords).

Suggestion:
Could "contains user-defined keywords" and "does not contain user-defined keywords" be added to Comparison operator (this would work only for (Item) attribute)?
Alternatively, even if one ticks "Search only user-defined keywords", it shouldn't apply to other than (Item) attribute, cause attributes themselves have only keywords and not "user-defined" keywords.

Thanks for consideration (and/or comments)