like this:
=$A$1&": "& IF(A2="","", TEXT(A2,"dd.mm.yyyy"))&" "&$B$1&": "& IF(B2="","",TEXT(B2,"dd.mm.yyyy"))&" "&$C$1&": "&C2&" "&$D$1&": "&D2&" "&$E$1&": "&E2&" "&$F$1&": "&F2