Samsung Galaxy S5 will be available by the end of next Month. However, its stock (pre-installed) Apps is currently available as an APK files, giving you a sneak peak on the New S5 UI & Apps and an early access to its features.
The leaked Apps are S Note, WatchON, Gear Manager, Gear Fit Manager, Calculator, S Health and S Translator.
These Apps will be installable on the Galaxy S4 and Galaxy Note 3 but would probably need you to be running Android 4.4.2 KitKat. S Health requires a hear monitor sensor which currently exists only on the Galaxy S5. Download the Apps From HERE at your own risk.