Getting user readable name via LDAP with PHP by having only the login credentials

I am integrating my login form with Microsoft active directory. I authenticate users via LDAP php library.

When user try to log in, they enter username & password. Connecting to server go successfully, authentication via "LDAP_bind" also give me true or false according to the values correctness. Now i am not able to retrieve the user Real name to display it on the screen.

ALL Information I have are the ldap uri with the port number, and username & password entered via the webform.

here is my current code,

$ldap = ldap_connect("ldap://abc.xyz:123");
if ($bind = ldap_bind($ldap, $_REQUEST['username'].'@abc.xyz',$_REQUEST['password'])) 
{ echo "Welcome". $_REQUEST['username'];}

the $_REQUEST['username'] is not human readable, so i need to read this user attributes or at least display name only.

ldap_search and ldap_read functions did not help, I tried this code:

$ldap_base_dn = 'DC=abc,DC=xyz';
$search_filter = "(objectclass=*)";
$result = ldap_search($ldap_connection, $ldap_base_dn, $search_filter);

with no luck, is there any other information i must have in order to make the ldap_search or ldap_read work successfully. in other words can this be done by having the username and password and the ldap uri only?