Display posts with a start OR end date later than current date

I’m working with an upcoming events list. I create a custom post type, with a custom field: [event_start_date]. I also have some multiday extension events, defined by an additional custom field: [event_end_date]. Then, I have this two kinds of events (examples):

• Birthday | start date: 13/08/2012, end_date: ’empty’
• Holidays | start date: 5/08/2012, end_date: 30/08/2012

I would like to display events with a ‘start’ or ‘end date’ later than current time, but I failed.

I think my date format is correct, because I had started using other ‘query’ that works perfect only using the [start date]. My problem is incorporating the ‘OR’ end_date condition. I tried with a meta_query with an ‘OR relation’, but doesn’t work:

$args = array(
             'post_type' => 'eventos2',
             'posts_per_page' => 4,
             'meta_key' => 'event_start_date',
             'orderby' => 'meta_value',
             'order' => 'ASC',
             'meta_query' => array(
             'relation' => 'OR',
             array('key'  => 'event_start_date',
                   'value' => date('Y/m/d', strtotime('-1 day')),
                   'compare' => '>=')

             array('key'  => 'event_end_date',
                   'value' => date('Y/m/d', strtotime('-1 day')),
                   'compare' => '>=')
             )
   );
$loop = new WP_Query( $args ); 
while ( $loop->have_posts() ) : $loop->the_post();
$end = DateTime::createFromFormat('Y/m/d', get_field('event_end_date')); 
$start = DateTime::createFromFormat('Y/m/d', get_field('event_start_date'));

if ($end !='') {  /*print events with start and end_date*/ 
    echo "<li>";
    echo the_title(), "</br>";
    echo $start-> format('Y/m/d'),"&nbsp". to . "&nbsp". $end-> format('Y/m/d'); 
    echo "</li>";
    }
    else {             /*print events with only start_date*/
    echo "<li>";
    echo the_title(), "</br>";
    echo $start-> format('Y/m/d');
    echo "</li>";   
    }
    endwhile;
   ?>

It show this result:

• EVENT 2 |
  2012/08/08 to 2012/08/15
• EVENT 4 |
  2012/08/31 to 2012/09/06
• EVENT 3 |
  2012/08/17
• EVENT 1 |
  2012/08/01

How you can see, EVENT 1 is listed, despite of is a past event. Moreover events are in disorder.

I will appreciate any orientation with the problem.