wicd-client: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/wicd-client - from package: wicd-common

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/wicd-client - from package: wicd-gtk

You may install the required package with command apt-get install {package}

Error in other languages:
wicd-client: bevel nie gevind nie
wicd-client: comandă negăsită
wicd-client: comando não encontrado
wicd-client: commande introuvable
wicd-client: command not found
wicd-client: käsku ei ole
wicd-client: không tìm thấy lệnh
wicd-client: komanda nerasta
wicd-client: Kommando nicht gefunden.
wicd-client: kommandot finns inte
wicd-client: komut yok
wicd-client: nie znaleziono polecenia
wicd-client: níor aimsíodh an t-ordú
wicd-client: no se encontró la orden
wicd-client: no s'ha trobat l'ordre
wicd-client: opdracht niet gevonden
wicd-client: parancs nem található
wicd-client: perintah tidak ditemukan
wicd-client: príkaz nenájdený
wicd-client: příkaz nenalezen
wicd-client: команда не найдена
wicd-client: командата не е открита
wicd-client: 命令找不到
wicd-client: コマンドが見つかりません