Adding multiple values in attribute

So here is shortcode that i can use to output names based on attributes.

For example, [my_site dfd_name="boy"] will output all boys name.
However if I put “girl” in the name attribute, it does not recognize it. ([my_site dfd_name="boy,girl"]).

Here is the full php:

<?php

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

    function sp_shortcode_listings($atts, $content = null, $code = "") {    

    global $wp_query;
    global $title;
    global $active_tab;
    global $showposts;
    global $sp_taxonomy;

    $defaults = array(
        'type'     => 'grid',
        'before' => '',
        'after'  => '',
        'wrap'   => 'div',
        'title' => '',
        'showposts' => '12',
        'type'=> 'grid',         
      );

    extract( shortcode_atts( $defaults, $atts ) );

    if ($showposts == 12) {
        $showposts = isset($_GET['showposts']) ? $_GET['showposts'] : '12';
    }

    $shorcode = "sc";

    if(!empty($atts))
    {
        foreach ( $atts as $key =>  $val)
        {       
            if(strstr($key, 'dfd'))
            {
                $metaquery[] = array(
                        'key' => $key,
                        'value' => $val,                            
                        'compare' => 'LIKE',
                        'terms' => explode(',',$val)
                                );  
            }                
        }            
    }

    if(empty($metaquery))
    {
        $shorcode = "";
    }

    global $active_tab;
    $active_tab = isset( $_GET[ 'type' ] ) ? $_GET[ 'type' ] : $type;
    include(my_site_dir . '/archive-filter.php');

    global $post;

    ob_start(); 
    if ( have_posts() ) 
    {   
        my_template_property_archive_content_main_shortcode();
    }
    else
    {
        echo apply_filters( 'my_site_no_match', 'Sorry, no name matched your criteria' ) ;
    }

    $output_string = ob_get_contents();             
    ob_end_clean();         
    $output = sprintf( '<%4$s class="sp">%1$s%3$s%2$s</%4$s>', $before, $after, $output_string, $wrap );

    wp_reset_query();
    return $output; 


}       

add_shortcode("my-listings", "sp_shortcode_listings");

?>

How can I change it so that I can add multiple values in the “dfd” attributes?

Thanks