You can change language in game client:
English game client: http://s01.geekpic.net/di-5QIIAP.png
Russian game client: http://s01.geekpic.net/di-E472PJ.png
Click on "System" ("Настройки"), "Language" ("Язык") and choose.
If you have problem with saving these settings, look this thread in section "General discussion".