Replace youTube height and width

Replace youTube height and width

dear sir / madam

we have YouTube code

<iframe width="560" height="315" src=" https://www.youtube.com/embed/MtbxtzufgTM" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

we want to replace 
width by 100%
and 
height by 100%

I want to do it using JQUERY

in php I am using 

$copy_date = $rows['detail'];// youtube code
$pattern = '/width="\d+"/i' ;
 $new_style = 'width="280"' ;
 $detail = preg_replace($pattern, $new_style, $copy_date) ;