In KDE, if you open the main menu (by the type of how to press the "Start" button in Windows) there is an item in one of the tabs, called "System settings" (in the local KDE "System Settings" ).
So there should be such a point as "Shortcuts and Gestures" ( "Shortcut Keys and Flips" ). Going into it, on the left in the panel there are three different menus. You need to select "Custom Shortcut" .
In the menu to the right you see the various folders (column with the name "Name") - choose "Examples". Next - either PCM or below there is an item "edit", choose: "new" -> "global shortcut" -> "Command\URL" - hang up a custom hotkey for some command, like dolphin \ chrome \ etc .. .
You can also play around with the rest of the items in the "global shortcut" sub-item.
ps I use Debian 8.2 myself, but it costs KDE 4. So, I hope that it helped.