Mac OSX 10.10.5 does not Search in Library folder? Why?

Mac OSX 10.10.5 does not Search inside the Library folder, that's a pity.

- All categories are selected in the Spotlight preferences in System Prefs.

- I tried the "System files - are included" trick, nothing.

- I tried the Search: "filename:the_actual_file_name" query trick, nothing.

Does someone know how to tweak Mac OS to perform Searches inside the Library folder???