如何根据前端的分类法搜索媒体？

以下查询显示我希望通过搜索返回的内容：

$args = array(
\'post_type\' => \'attachment\',
\'post_status\' => \'inherit\',

// for PDFs    
\'post_mime_type\' => \'application/pdf\',

// if you need PDFs from a specific media category
\'tax_query\' => array(
    \'relation\' => \'AND\',
    array(
        \'taxonomy\' => \'media_category\', // taxonomy
        \'field\' => \'id\',
        \'terms\' => 21 // term id (STATIC id of the media category)
        ),
    array(
        \'taxonomy\' => \'media_category\', // taxonomy
        \'field\' => \'id\',
        \'terms\' => 22 // term id I NEED TO SET VIA SEARCH)
        )
    )
);