1. Backup database and old magento files.
2. Download latest magento.
3. Download bash script upgrade.sh here ( Note: this script copies all custom files and folders from older magento to latest magento path )
4. Run command as 
	$./upgrade.sh old_magento_path latest_magento_path 
5. Remove all files from old_magento_path and copy all files from latest_magento_path to old_magento_path.
6. Refresh cache.