wp-login problem with php 5.6

hi,
I migrate my web site to another server with same url

my new server works with php 5.6.
the problem is that can’t login, front end and back end.
White screen and i have the errors:

Warning: Cannot modify header information – headers already sent by (output started at /home/xxx/public_html/wp-config.php:1) in /home/xxx/public_html/wp-login.php on line 390

Warning: Cannot modify header information – headers already sent by (output started at /home/xxx/public_html/wp-config.php:1) in /home/xxx/public_html/wp-login.php on line 403

when i turn to php version 5.3 work fine,(i can login) front and back end.
(only with php5.3 work, i try and others versions 5.4, 5.5)

But its necessary to stay in php5.6

Any Idea???