I need help in get_posts function with ajax file

Hi,
I’m trying to create a buddy press component, I want to retrieve posts based on custom filed using meta_query of the get_posts word press functions from an ajax function in buddy press component ajax file,
I wrote my $args as flowing:

$args = array(

‘s’=>$keyword ,

‘post_type’ => ‘businesspost’,
‘post_status’ => array(‘publish’),
‘orderby’ => ‘post_date’,
‘showposts’=>10,

‘meta_query’ => array(
array(‘key’ => ‘_offertype’, ‘value’ => ‘sellofer’
) )
);
$posts=get_posts($args);

If i delete the meta_query it gives posts fine, but when i add the meta query it gives nothing, I’m sure that my custom field key and value are correct.
please some one helping me.