search in every type of content

Hi all,
I'd like to ask if there is a possibility to search key words not only in issues names or only in description.
It would be much convienient to search everywhere in one step, i.e. in names, descriptions, comments etc.

Is it possible to change any function by myself to be able to search the content this way?
Could you tell me where the searching function is?

I'd would be grateful.

Regards,
Bernard