Answer

Simply run the svn client with the version argument and it would echo back the SVN client version.

mymac:ios-apps mvohra$ svn --version
svn, version 1.6.17 (r1128011)
   compiled Nov  8 2011, 18:14:46

Copyright (C) 2000-2009 CollabNet.
Subversion is open source software, see http://subversion.apache.org/
This product includes software developed by CollabNet (http://www.Collab.Net/).<!>

In order to find the SVN Server version use

mymac:ios-apps mvohra$ svnadmin --version
svnadmin, version 1.6.17 (r1128011)
   compiled Nov  8 2011, 18:14:46

Copyright (C) 2000-2009 CollabNet.
Subversion is open source software, see http://subversion.apache.org/