To change the language of the game Unreal Tournament 3 to Russian, you must:
1) Open in the user folder Documents\My Games\Unreal Tournament 3\UTGame\Config
2) Find the UTEngine.ini file there and open it in a text editor.
3) In [Engine.Engine] find the line Language=INT and replace INT with RUS to get Language=RUS.
Save the changes and the next time you launch Unreal Tournament 3, the text and voice acting should be in Russian.