Если я вас правильно понял, то:
<label for="demo1" onclick="" class="radiobutton option_2"></label>
<label for="demo2" onclick="" class="radiobutton option_3"></label>
<label for="demo3" onclick="" class="radiobutton option_4"></label>
<input type="radio" name="compane" id="ulu" value="option_1">
<input type="radio" class="option_2" name="compane" id="demo1" value="option_2">
<input type="radio" class="option_3" name="compane" id="demo2" value="option_3">
<input type="radio" class="option_4" name="compane" id="demo3" value="option_4">
$(document).ready(function () {
$('input:radio', ".form-group").change(function () {
$('label.radiobutton.' + $(this).attr("class")).addClass('custom_checkbox');
});
});