The define(‘WP_DEBUG_LOG’, true); will log errors into the debug.log file in the wp-content directory, @ini_set(‘log_errors’,’On’); allows you to specify the file where you want to save it. This should work for you:
@ini_set('log_errors', 1);
@ini_set('display_errors', 0); /* enable or disable public display of errors (use 'On' or 'Off') */
@ini_set('error_log', dirname(__FILE__) . '/wp-content/logs/your-error-file.log'); /* path to server-writable log file */
@ini_set( 'error_reporting', E_ALL ^ E_NOTICE ); /* the php parser to all errors, excreportept notices. */