I've recently run into this issue as well...
Execute-Process -FilePath "LOTUS_Notesclient_853_WIN_EN_EVA.exe" -Arguments '/s /v" /qn"'
Has not been working for me. The installer requires the exact syntax of .exe /s /v"/qn". I've even tried doing .exe "/s /v/qn" which has worked for me on another .exe installer, but not for this one.