<option value="NOT REGEXP"> NOT REGEXP </option>
                <option value="RLIKE"> RLIKE </option>
            </select>
            <span><input type="text" name="meta_value[]" class="meta_value primary" placeholder="Search for value"></span>
            <!-- Search Button -->
            <span><input type="submit" class="btn_get button-primary" name="search_user" value="Search" /></span>
        </div>
        <!-- <div> has class to separate search & table with hidden bar -->
        <div class="line-separator"></div>
        <span class="no_items">0 item</span>
        <!--table for showing data-->
        <input type="hidden" name="export_by_id" class="export_by_id" value="" />
        <table class="wp-list-table widefat fixed striped">
            <thead class="tbl_header">
            <?php 
$speu_obj = new SPEU();
$final_fields = $speu_obj->getFieldSearch();
$final_fields_value = array_values($final_fields);
foreach ($final_fields_value as $tbl_header) {
    echo '<th style="font-weight:bold;">' . $tbl_header . '</th>';
}
?>
            </thead>
            <tbody class="show_content">
            <td>No Data</td>
            </tbody>
        </table>
        <p class="submit">
            <!-- Export Buttton -->
            <input type="submit" class="button-primary export_csv" name="download_csv" value="Export" disabled />
        </p>
 public static function getInstance()
 {
     if (self::$instance === null) {
         self::$instance = new self();
     }
     return self::$instance;
 }