<div class="open_case_field_wrap">
                    <input type="text" value=""><span class="help_wrap"><span class="help_icon">?</span><span class="help_text">ТЕКСТ 1</span></span>
                </div>
                <div class="open_case_field_wrap">
                    <textarea name="desc"></textarea><span class="help_wrap"><span class="help_icon">?</span><span class="help_text">ТЕКСТ 2</span></span>
                </div>

$('.help_icon').click(function() {
        $(this).parent('.help_wrap').toggleClass('help_info_open');
    });