meta query regexp only work with first two characters

I have a meta query to return data based on the input value. Here I get value like this Tm-university-brazil,

now I replace the dash with space so it becomes Tm university brazil, but the search does not work, it only works if put ‘Tm’ in search it does not work when ‘Tm university brazil’.

if (isset($  uni_name)  && !empty($  uni_name)  ) {  $  uni_name = str_replace('-'," ",$  uni_name);       $  meta[] = array(             'key'     => 'uniname',             'value'   => $  uni_name,             'compare' => 'REGEXP',                  );  }