[otrs] OTRS 3.1: Making dynamic fields searchable

Hi, I recently successfully upgraded from OTRS 3.0.x to 3.1.3 and all Free Fields were converted into Dynamic Fields. But I now sadly miss the possibility to use them in a search. This was possible with Free Fields in OTRS 3.0.x. Google and the OTRS documentation didn't help. Can anyone give me a hint, how Dynamic Fields can be made searchable? Thanks in advance frank