Javascript regex allow only \w and exceptional characters

var string = "Ç<>iğ^%+/dem Öçğö";
var check_w = string.search(/\w/g); //sadly this not accept "öığüşç" characters
var check_utf = string.search(/[öığüşç]/gi);

if (check_w != -1 && check_utf != -1) {
   var replace = string.replace(/\W/gi, '');
   document.write(replace); //result is: "idem" but i want result: "Çiğdem Öçğö"
}
else if (check_w != -1 && check_utf == -1) {
  var replace = string.replace(/\W/gi, '');
  document.write(replace); //no problem
}
else if (check_w == -1 && check_utf != -1) {
  //i dont know how to replace other characters but not "öığüşç" that characters. For example: <öı^&^ğ i want result: öığ
}
else if (check_w == -1 && check_utf == -1) {
  alert('error'); //no problem
}

İ don't know how to use "check_utf" variable to make exceptional...

Edit: Normally i use replace to only replace special characters but i want make like this because i dont want to allow china arabia characters etc...(like make whitelist)