Nested array issue in meta_query

I am using following meta_query to search blog post according to following search criteria,

search logic :

1. if expire date set, check the expiry of the post, otherwise just include it
2. if country($_country) in the filters, search for that particular country with above expire date rule. otherwise just apply the expire date rule.

meta_query:

$expire_meta_1 = array(
    'key' => '_simple_fields_fieldGroupID_3_fieldID_7_numInSet_0',
    'value' => '',
    'compare' => 'NOT EXISTS'
);

$expire_meta_2 = array(
    'key' => '_simple_fields_fieldGroupID_3_fieldID_7_numInSet_0',
    'value' => date("Y-m-d"),
    'compare' => '>=',
    'type' => 'DATE'
);

if($_country!=''){
    $country_meta = array(
        'key' => '_simple_fields_fieldGroupID_3_fieldID_8_numInSet_0',
        'value' => $_country,
        'compare' => '='
    );
    $args['meta_query'] = array( 'relation' => 'AND', array( 'relation' => 'OR', $expire_meta_1, $expire_meta_2), $country_meta);
} else{
    $args['meta_query'] = array( 'relation' => 'OR', $expire_meta_1, $expire_meta_2);
}

the issue is, if it is country search, post should set the expire date. but I need to select the posts also not set the expire date.(if set check the expiry, that is anyway working).

But if I am not searching for specific country, the expire date rule(rule 1) is working properly.

Anybody have any idea what is my mistake. Any help would be appreciate.
I hope question is clear, otherwise I can provide more details, please let me know.
Thanks in advance.