Equivalent for Windows + R for Android It's often difficult to locate the app I am looking for on my Android phone. Is there a way/app which behaves like Windows + R on a PC, with autocomplete, so that I can quickly launch the app I want to use, rather than endless swiping?
Most custom and stock launchers for Android support an "app search" feature. I know that ADW.Launcher, Nova Launcher, Apex Launcher, Google Now Launcher and Google Now itself has this feature. I'll tell you how to access this feature with Google Now (Launcher) and Nova Launcher, because I have those on hand to confirm this procedure.

For Google Now (or the stock Search app):

Enter the app's name into the home screen search box/widget. It should an option for the app, tapping on which should launch it.

If your Google Now has "OK Google" voice commands active and properly configured, saying OK Google, launch &lt;app's name as shown in the launcher&gt; or OK Google, open &lt;app's name as shown in the launcher&gt; to the device should also work from the home screen.

For Nova Launcher:

On the App Drawer page, swipe down from the top, to get a magnifying glass icon on small white circle in the top-center of the page. Pull it down further to get the search bar. Entering the app's name in the search bar should show its icon below the bar, and tapping on that icon will launch the app.

This applies to Nova Launcher version 4 and up. Apex Launcher is very similar to Nova, but I'm not sure this works there too. The latest version of Nova, 4.2.0, also has the "Recently used apps" feature like Google Now Launcher below.

For Google Now Launcher:

Same as Google Now above, but it also has a separate search bar on its app drawer page. It also shows your most recently used apps at the top of the app drawer's first page.

This should get you started. Welcome to the mini-universe of Android's custom launchers!