Escape the regex character from a Searching String

Question

We use a Regex for matching text such as follow

       String  str =".*" + s + ".*";

here - s is user enter text

  if(stringtext.matches(str .toLowerCase())){
           return true;
   }

above code is working fine when user enter plain text.
but user enter any regex character such as e.g. (,},},^,$ etc it gives java.util.regex.PatternSyntaxException: Unclosed group near index 5 .(.