The Spotify client is available through WINE or natively through the AUR. I’ll walk you through the AUR way.
1. Download the Spotify package from the AUR. [Spotify AUR]
2. Unpack the package and compile.
tar -zxvf spotify.tar.gz
The “-s” switch will use pacman to resolve any dependencies.
3. Install the compile package.
pacman -U spotify-0.9.4.183-2-x86_64.pkg.tar.xz