Merge arrays and order set and subset as one

You can check get_post_meta before args, Example:

// Get post meta
$game = get_post_meta($post->ID, 'sd_game', true);
$game_series = get_post_meta($post->ID, 'sd_game_series', true);

// Check which meta
if( !empty(  $game ) ) {
    $key = 'sd_game';
} else {
    $key = 'sd_game_series';
}

$posts = get_posts(array(
    'numberposts'   => -1,
    'post_type' => 'lyric',
    'meta_query'    => array( 
       array(
          'key' => $key,
          'value' => '',
          'compare' => '!='
       ), 
       array(
          'key' => 'sd_game_type',
          'value' => '-Original-',
          'compare' => '!='
       )
);

Hope this helps you 😉