Can't connect using SqlManager for Oracle, but Sql+
After installing 32-bit Oracle client software on a 64-bit Windows
  operating system (OS) you receive one of the following errors:
  ORA-12154 / ORA-06413.
  
  Cause   64-bit Microsoft OS's install 32-bit applications into   C:\Program Files (x86)\... rather than the typical location of
  C:\Program Files\....
  
  This causes an existing networking bug to occur where the networking
  layer is unable to parse program locations that contain parenthesis in
  the path to the executable which is attempting to connect to Oracle.
  
  Solution   Find the location of the application that is generating the error.  Check the path to this location and see if it contains any
  parenthesis.  If so, you must relocate the application to a directory
  without any parenthesis in the path.


I just moved Sql Manager to 64-bit applications install path (I know it's not super "clean", but nevermind) and now it works correctly.

Found answer here: MSDN connecting to oracle on 64bit x64 machine