<?php
 
function preg_grep_keys_values($pattern, $input, $flags = 0) {
    return array_merge(array_intersect_key($input, array_flip(preg_grep($pattern, array_keys($input), $flags))),
    		preg_grep($pattern, $input, $flags));
}
 
$a = array(
  'mark@test.by.com'=> "Mark Mian lv",
  'jhon@test.lv.com'=> "John jack lv",
  'logon@test.en.com'=> "Bob Logon",
  'Stela@test.es.com'=> "Stela Josh",
  'json@test.es.com'=> "Json Josh",
  'bobby@test.lv.com'=> "Bob Mark"
);
 
$r = preg_grep_keys_values('~lv~i', $a);
print_r($r);

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