Hi Marcin,
Sorry, I dint see your query properly. Ok let me tell you the steps.
You dont need to really enhance the context Node 'Search' unless and until the field is available in the 'Selected Search Criteria'. Assuming that you have the both the field in the screen when you login to WebUI. Perform the search as you did in GUI and let me know the results.
I have F4 available in my screen. I just pulled the field and see screens below.
Please try once again.
Regards,
Karthik