これを変える
oUserTable.fnFilter($(this).val(), 12);
に
oUserTable.fnFilter("^"+$(this).val()+"$", 12, false, false);
//disabling smart search/regex and apply your own search
例
ドク
のパラメータfnFilter
1.{string}: String to filter the table on
2.{int|null}: Column to limit filtering to
3.{bool} [default=false]: Treat as regular expression or not
4.{bool} [default=true]: Perform smart filtering or not
5.{bool} [default=true]: Show the input global filter in it's input box(es)
6.{bool} [default=true]: Do case-insensitive matching (true) or not (false)