Custom search by several options send on form not works

put value of keys and check results.(use get_users function to query users)

$args=array(
    'relation'=>'AND'
);
if(isset($_GET["nome_of_city"])){
    $arg[]=array(
            'key' => 'your_key_name_1',
            'value' => $_GET["nome_of_city"]
        );
}
if(isset($_GET['name_of_neighborhood'])){
    $arg[]=array(
        'key' => 'your_key_name_2',
        'value'=>$_GET['name_of_neighborhood'],
        'compare'=>'IN'
        );
}
if(isset($_GET['name_of_course'])){
    $arg[]=array(
        'key' => 'your_key_name_3',
        'value'=> $_GET['name_of_course'],
        'compare'=>'IN'
        );
}
$users=get_users($args);
 foreach ($users as $user) {
        echo '<li>' . $user->user_email . '</li>';
    }

Important Link:

get_users()